zntg/ui/checkbox.go

package ui

import (
	"fmt"
	"image"
	"image/color"

	"github.com/llgcode/draw2d/draw2dimg"
	"github.com/llgcode/draw2d/draw2dkit"
	"opslag.de/schobers/galleg/allegro5"
	"opslag.de/schobers/geom"
)

type CheckboxValueChangedFn func(bool)

func createOnBitmap(fill, stroke color.Color) *allegro5.Bitmap {
	var sz = float64(checkboxSize)
	on := image.NewRGBA(image.Rect(0, 0, checkboxSize, checkboxSize))

	gc := draw2dimg.NewGraphicContext(on)
	gc.SetFillColor(color.Transparent)
	gc.Clear()
	gc.SetFillColor(fill)
	draw2dkit.RoundedRectangle(gc, 0, 0, sz, sz, 3, 3)
	gc.Fill()

	gc.SetStrokeColor(stroke)
	gc.SetLineWidth(2)
	gc.MoveTo(2.5, 5.5)
	gc.LineTo(5.5, 8.5)
	gc.LineTo(10, 3.5)
	gc.Stroke()

	bmp, err := allegro5.NewBitmapFromImage(on, false)
	if nil != err {
		return nil
	}
	return bmp
}

func createOffBitmap(fill, stroke color.Color) *allegro5.Bitmap {
	var sz = float64(checkboxSize)
	off := image.NewRGBA(image.Rect(0, 0, checkboxSize, checkboxSize))

	gc := draw2dimg.NewGraphicContext(off)
	gc.SetFillColor(color.Transparent)
	gc.Clear()
	gc.SetFillColor(stroke)
	draw2dkit.RoundedRectangle(gc, 0, 0, sz, sz, 4, 4)
	gc.Fill()
	gc.SetFillColor(fill)
	draw2dkit.RoundedRectangle(gc, 1, 1, sz-1, sz-1, 3, 3)
	gc.Fill()

	bmp, err := allegro5.NewBitmapFromImage(off, false)
	if nil != err {
		return nil
	}
	return bmp
}

type Checkbox struct {
	ControlBase
	Value     bool
	Text      string
	OnChanged CheckboxValueChangedFn
	on        *allegro5.Bitmap
	off       *allegro5.Bitmap
}

func (c *Checkbox) Created(ctx Context, p Container) error {
	var err = c.ControlBase.Created(ctx, p)
	if nil != err {
		return err
	}
	var plt = ctx.Palette()
	c.on = createOnBitmap(plt.Primary(), plt.White())
	c.off = createOffBitmap(plt.White(), plt.Black())
	if nil == c.on || nil == c.off {
		return fmt.Errorf("error creating checkboxes")
	}
	return nil
}

func (c *Checkbox) Handle(ctx Context, ev allegro5.Event) {
	var pressed = c.IsPressed
	c.ControlBase.Handle(ctx, ev)
	switch ev.(type) {
	case *allegro5.MouseButtonUpEvent:
		if !c.Disabled && pressed && c.IsOver {
			c.Value = !c.Value
			var onChanged = c.OnChanged
			if nil != onChanged {
				onChanged(c.Value)
			}
		}
	}
}

func (c *Checkbox) DesiredSize(ctx Context) geom.PointF {
	var fonts = ctx.Fonts()
	var fnt = fonts.Get("default")
	var w = fnt.TextWidth(c.Text)
	return geom.PtF(float64(w+2*leftMargin+checkboxSize), 24)
}

func (c *Checkbox) box() *allegro5.Bitmap {
	if c.Value {
		return c.on
	}
	return c.off
}

func (c *Checkbox) Render(ctx Context) {
	var fonts = ctx.Fonts()

	var min = c.Bounds.Min.To32()
	min = geom.PointF32{X: min.X + leftMargin, Y: min.Y + topMargin}

	var fnt = fonts.Get("default")

	var _, textY, _, textH = fnt.TextDims(c.Text)
	fnt.Draw(min.X+leftMargin+checkboxSize, min.Y-textY, ctx.Palette().Black(), allegro5.AlignLeft, c.Text)
	var checkboxTop = min.Y + textH - checkboxSize
	if c.Disabled {
		var disabled = ctx.Palette().Disabled()
		c.box().DrawOptions(min.X, checkboxTop, allegro5.DrawOptions{Tint: &disabled})
	} else {
		c.box().Draw(min.X, checkboxTop)
	}

	c.ControlBase.Render(ctx)
}